Pressing iron having an electro-osmotic pump

ABSTRACT

A clothes iron appliance composed of a water reservoir, a steam chamber, and an electro-osmotic pump having a porous body disposed to pump water from the reservoir to the steam chamber.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to steam pressing irons, andsimilar appliances such as steam wrinkle removers. In such appliances,water is conveyed slowly from a reservoir to a steam chamber in whichwater is converted into steam. More particularly, the invention concernsmeans for conveying the water into the steam chamber.

[0002] The most well known devices for this purpose are drip devicesfunctioning by gravity, but they have the drawback that they cease tofunction when the pressure of steam in the steam chamber becomes higherthan that of the column of water available above the drip device.

[0003] One solution to this problem consists in adapting anelectromagnetic piston or membrane pump actuated by an electromagnet oran electric motor. Such devices are described, for example, in Frenchpatents numbers FR2368862 and FR2690932. Also known are rotary pumpssuch as centrifugal pumps as described in French patent number FR2688013as well as peristaltic pumps, an example of which is disclosed in Frenchpatent number FR2691210, less commonly used.

[0004] These types of pumps have proven satisfactory with regard to flowrate and pressure. However, they also generate noise and vibrations,their flow rate is not easily variable, which leads them to operate inbursts, and they are relatively costly.

BRIEF SUMMARY OF THE INVENTION

[0005] The present invention provides a household electric appliancecontaining a water reservoir that may be filled with tap water and thatis equipped with a pump that is silent, economical and durable totransfer water from the reservoir toward the steam chamber, with acontinuous flow rate that is easily adjustable with precision and isinterruptible, as well as having a sufficient pressure to overcome thecounter pressure generated in the steam chamber during ironing.

[0006] Primarily, the invention is embodied in an ironing appliancehaving a water reservoir and a pump for transferring water from thereservoir toward the steam chamber, wherein the pump is anelectro-osmotic pump.

[0007] An electro-osmotic pump, as contemplated by the presentinvention, is a device having a first compartment that is normallyconnected to the water reservoir or that forms a part of this reservoir,and a second compartment connected to the steam chamber in which watertransferred by the pump is converted into steam, the two compartmentsbeing separated by a porous solid body. Each compartment is furnishedwith an electrode in proximity to the porous body, the electrodesallowing water to flow therepast.

[0008] Thus, when a voltage is applied between the electrodes, a flow ofwater is created from the first compartment toward the secondcompartment and supplies the steam chamber. The principle of anelectro-osmotic pump is described for example in U.S. Pat. No.3,143,691. This document cites the pressures obtained with water, whichreach the equivalent of a height of water of 11 mm per volt appliedbetween the electrodes. However, the device described only transferswater from one chamber to another without flowing in a circuit, orserves to detect a pressure or flow rate.

[0009] Uses are known in fields that are radically different from thatof the present invention. For example, French patent FR1446109 describesnumerous devices using a pump of this nature, but with non-aqueousliquids. Several patents also describe medical uses for distributingmedications in very small quantities, uses in chromatography to cause anelectrolyte to circulate in a column, and uses in fluidics with low flowrates as in U.S. Pat. No. 6,012,902.

[0010] All of these uses concern movements of electrolytes or diversesolutions having characteristics far removed from running water,generally in fields that are very sophisticated and that involve lowflow rates.

[0011] French patent FR2467178 describes a water purifier usingelectro-osmotic pumps, but the pumps used only operate if the water ispurified, by resin devices that demineralize the water.

[0012] None of the above-cited documents envisions or suggests theutilization of such a pump in a household electric appliance, or evenless in a pressing iron. However, an iron provided with anelectro-osmotic pump performs particularly well and is particularlyquiet.

[0013] The pump is placed between the reservoir and the steam chamber.Its water inlet communicates with the reservoir or is located within thereservoir, while its outlet is connected to the steam chamber.

[0014] According to one embodiment, the pump is constituted by anenclosure made of electrically non-conductive plastic, containing aporous body composed of grains of fritted glass, in the form of a discoccupying the entire cross-section of the enclosure. The fluid inlet andoutlet are arranged at respective opposite sides of the porous disc. Twoelectrodes are placed to one side and the other of the disc, in contactwith the fritted glass and in the path of the fluid. The pump isactuated by application of a direct voltage between the electrodes, ofthe order of 10-200 volts. Water is displaced, in this case of asiliceous covering of the disc, from the anode toward the cathode, theflow/pressure characteristic being linear and being directly dependanton the applied voltage.

[0015] Preferably, the cross-section of the porous body corresponding tothe water passage has dimensions greater than the thickness of theporous body.

[0016] Specifically, the diameter of the disc is greater than itsthickness. This thus avoids having a localized bubble in the porous bodyinterrupt the passage of the electric current and the operation of thepump. In effect, a possible gas bubble, generated by the electrodes andtrapped in the porous body, cannot have a diameter greater than thethickness of the porous body and thus cannot obstruct the entire passagecross-section for the water and the electric current.

[0017] In a preferred embodiment, the porous body is constituted by abed of grains of very fine alluvial sand having a grain size of 0.2 mmor less.

[0018] Thus, fritted glass is replaced by the sand. This provides aneconomical form of construction of the medium in which theelectro-osmosis is produced. Preferably, the porous body is of asiliceous nature, such as a quartz sand.

[0019] The bed of grains is maintained in an enclosure made of plasticby the electrodes, which are preferably made of stainless steel andprovided with holes, the electrodes being placed on two flat faces ofthe bed.

[0020] Preferably, the electrodes are made of sheets of stainless steelthat are perforated and expanded.

[0021] The electrodes do not significantly interfere with the passage ofwater in the pump.

[0022] Preferably, the electrodes are separated from the bed of grains,which they retain, by porous membranes.

[0023] The membranes aid retention of the sand so that the perforationsin the electrodes do not have to be particularly small.

[0024] The electric supply of the pump, for reasons of safety, includesa transformer or a switch mode power supply including a galvanicisolation.

[0025] The invention also permits a linear variation of the flow rate bymodification of the direct voltage applied between the electrodes.

BRIEF DESCRIPTION OF THE DRAWING

[0026]FIG. 1 is an elevational, cross-sectional view of an ironaccording to the invention.

[0027]FIG. 2 is a cross-sectional detail view, to a larger scale thanFIG. 1, of a preferred embodiment of a pump according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0028] According to a preferred embodiment, shown in FIG. 1, a steamiron 1 includes an integrated water reservoir 11, and a soleplate 12heated by a heating body 13 furnished with a heating element 131. Asteam chamber 132, closed by a plate 133, is arranged in heating body13. Steam produced in chamber 132 escapes through steam holes 121 in theironing face of soleplate 12.

[0029] An electro-osmotic pump 2 is installed at the rear of waterreservoir 11. Preferably, the pump is present in the form of a cassette21 introduced into the bottom of reservoir 11 from the rear of the iron,before closing the heel of the iron by the heel piece 14 duringfabrication of the iron. A sealing joint 211 assures a liquid tight sealbetween the cassette and the wall of reservoir 11. As a result of thisarrangement, the pump is easily removable and replaceable when iteventually becomes ineffective. At the rear of the iron, the pumpremains immersed in water even when the iron is placed on its heel piece14.

[0030] As shown in FIG. 2, pump 2 has a water outlet 212 that isaccessible to the exterior to the reservoir. Water outlet 212 isconnected to a point 134 at which water is injected into steam chamber132 through a conduit 15. Conduit 15 has at a high point along its patha shunt 151 toward a high point of reservoir 11. Shunt 151 is providedwith a calibrated orifice 152, opening into the high point of reservoir11, with a diameter of several tenths of a millimeter, which is smallrelative to the diameter of conduit 15.

[0031] With this arrangement, introduction of air through orifice 152interrupts any siphoning from reservoir 11 toward steam chamber 132 whenthe iron ceases being used but remains with the soleplate flat on theironing surface. In effect, this siphon action, although very slow dueto the substantial loss of head in pump 2 when it is halted, would bepossible since reservoir 11 is placed higher than the point 134 at whichwater is injected into steam chamber 132. When the pump is in operation,the flow of water toward reservoir 11 through orifice 152 is negligible.

[0032] Further referring to FIG. 2, pump 2 includes an envelop 21 in theform of a cassette, divided vertically into two compartments 213, 214.These two compartments are separated by a porous body 220 that may be inthe form of a disc. Preferably, the disc has a circular, cylindricalform, with an axis that is vertical in the plane of FIG. 2. According toa preferred embodiment of the invention, body 220 has a diameter of theorder of 40 mm, and a thickness of 10 mm. However, disc 220 can have anyother outline that is compatible with the internal configuration of thereservoir. Disc 220 is enclosed laterally by a ring 221, preferably madeof electrically insulating plastic material, this ring facilitatingfabrication of the body. Ring 221 is clamped in cassette 21 by internalparts 215, which helps to assure the formation of a fluid tight sealaround ring 21 between compartments 213 and 214.

[0033] Porous body 220 is preferably constituted by a bed of alluvialsiliceous sand having a grain size of less than 0.2 mm. Each exposedface of disc 220 is covered with a membrane 22 and an electrode 223.Each membrane 22 is permeable to water, and may be made, for example, offilter paper, and each membrane 22 is in contact with body 220. Eachelectrode 223 overlies its associated membrane 222 and may be made of anexpanded stainless steel sheet that serves to retain the shape of theporous body. Each electrode is connected by a soldered connection 224 toa pin, such as 216, that passes through the wall of cassette 21 that isoutside reservoir 11. According to another form of construction, theelectrodes can be made of an expanded titanium sheet, preferably havinga platinum coating.

[0034] A connector (not shown) connects pins 216 to a direct currentsource, with the lower electrode being the anode and the upper electrodebeing the cathode. The direct current source can be disposed in thehandle of the iron and can be a transformer or a switch power supplyincluding a galvanic isolation with respect to the power mains and thebody of the iron. Voltage applied between the electrodes duringoperation of pump 2 can be regulated by the user, from 10 to 200 volts.

[0035] Lower compartment 213 of pump 2 is open at the bottom andlaterally to communicate with the interior of reservoir 11 so that watercontained in reservoir 11 will enter compartment 213 and moisten body 20by capillarity. Upper compartment 214 is coupled to pump outlet 212.

[0036] When the iron is ready to be used and the user wishes to producesteam, he adjusts the output voltage of the constant current source byacting on a suitable button or switch that can be graduated in terms ofsteam flow rate. The voltage applied between electrodes 223 provokes anion current along the walls of the capillary network constituted by thegrains of sand, thus entraining molecules of water in the direction ofthe cathode in the case of a porous siliceous body. Water passes fromreservoir 11 into compartment 213 then through body 220, intocompartment 214 and then out through outlet 212, which may be in theform of a nipple, and finally through conduit 15, in order to reachpoint 134 where water is injected into the steam chamber.

[0037] The thickness of the porous body being constant, the water flowrate is directly proportional to the voltage applied between theelectrodes. If there is a slight liberation of gas at the electrodes dueto electrolysis of the water, the gas forms into bubbles. The diameterof the bubbles cannot exceed the thickness of the disc constituting body220, which thickness is less than the diameter of the body. Therefore,the bubbles cannot completely interrupt the ion current between theelectrodes and can thus not cause an undesired blockage of pumpoperation. On the contrary, these bubbles will be entrained andevacuated along with the water current.

[0038] The device as described produces, when supplied with a directvoltage of 200 volts, a water flow rate of around 20 g/min under apressure of several tens of millibars, much greater than the column ofwater available in the iron above injection point 134, fully sufficientto overcome the counter pressure due to the steam produced in chamber132 and to assure easy ironing. Since there is no mechanical movingpart, the pump operation is completely silent.

[0039] When the user finishes ironing, and if he allows the iron to coolwhile left to rest on soleplate 12, conduit 15 empties slowly throughinjection point 134. Air inlet 152 prevents water from beinginadvertently siphoned out of reservoir 11, through pump 2.

[0040] In a related form of construction, conduit 15 has, upstream ofshunt 151, a 3-way valve that permits, under control of the user, thesupply of water to a sprayer 16 situated at the front of the iron inorder to moisten items to be ironed.

[0041] According to another form of construction, porous body 222 isconstituted by a bed of mixed grains including grains of ion exchangeresin having a small grain size. The polarity of the direct currentsource is selected as a function of the nature of the majority of thegrains. The porous body has the double function of a capillary substratefor the electro-osmosis, and a demineralizing system. Water outlet 212and the associated end of conduit 15 are modified to facilitate a rapidconnection suitable for a relatively frequent replacement of thecassette necessitated by the limited lifetime of such resins.

[0042] By these means, there is obtained an ironing appliance having apump that is silent, economical, reliable and durable for transferringwater from the reservoir toward the steam chamber with an easilyregulatible constant flow rate and with a pressure sufficient toovercome the counter pressure generated in the steam chamber as a resultof the generation of steam during ironing.

[0043] This application relates to subject matter disclosed in FrenchApplication number FR 03 01031, filed on Jan. 30, 2003, the disclosureof which is incorporated herein by reference.

[0044] While the description above refers to particular embodiments ofthe present invention, it will be understood that many modifications maybe made without departing from the spirit thereof. The accompanyingclaims are intended to cover such modifications as would fall within thetrue scope and spirit of the present invention.

[0045] The presently disclosed embodiments are therefore to beconsidered in all respects as illustrative and not restrictive, thescope of the invention being indicated by the appended claims, ratherthan the foregoing description, and all changes which come within themeaning and range of equivalency of the claims are therefore intended tobe embraced therein.

What is claimed is:
 1. A clothes iron appliance comprising: a waterreservoir; a steam chamber; and an electro-osmotic pump comprising aporous body disposed to pump water from said reservoir to said steamchamber.
 2. The appliance of claim 1 wherein said porous body has athickness dimension in the direction in which water is pumped, and across-section perpendicular to the thickness dimension, and thecross-section has dimensions greater than the thickness dimension. 3.The appliance of claim 1, wherein said porous body is composed of a bedcomposed of fine grains.
 4. The appliance of claim 3 wherein the finegrains are constituted by alluvial sand having a grain size not greaterthan 0.2 mm.
 5. The appliance of claim 3 wherein the fine grains are ofa siliceous material.
 6. The appliance of claim 3 wherein the finegrains include grains of an ion exchange resin.
 7. The appliance ofclaim 1 wherein said pump further comprises an enclosure made of plasticmaterial and containing said porous body, and two electrodes placed inelectrical communication with respective opposite faces of said porousbody.
 8. The appliance of claim 7 wherein each of said electrodes ismade of stainless steel or of titanium and is provided with throughholes.
 9. The alliance of claim 7, wherein said pump further comprisesporous membranes interposed between said body and said electrodes. 10.The appliance of claim 1 wherein said appliance further comprises asource of direct current for said pump, said source comprising atransformer or a switch mode power supply having a galvanic isolation.11. The appliance of claim 1 wherein said pump is constituted by acassette which is installed in said reservoir in an easily removablemanner, and said appliance further comprises a conduit connected toconvey water from an outlet of said pump to an inlet of said steamchamber.
 12. The appliance of claim 11 wherein said appliance furthercomprises a shunt provided with a calibrated orifice and connectedbetween a point of said conduit that is above said steam chamber and apoint in an upper region of said reservoir.
 13. The appliance of claim11, further comprising a spray nozzle and a 3-way valve connectedbetween said conduit and said nozzle for supplying water from said pumpto said nozzle.